Back in 2012, Democrats won 48.8% of the popular vote in congressional races to the Republican's 47.6%, a lead of over 1.4 million votes nationwide. Despite that, Republicans had a margin of 33 seats, easily retaining control.
To some extent, Democrats suffer because of geographical sorting, in which Democratic voters disproportionately congregate in cities. However, that cannot account for the full disparity. The gerrymandering done by Republicans after sweeping the legislatures and governorships in 2010 had a major impact as well. Republicans had full ability to draw Democrats out of their seats.
New research from Duke shows just how significant an impact gerrymandering had on the results in North Carolina in 2012:
Focusing on the last election, the researchers varied the state’s congressional districts to calculate what the outcome of the 2012 U.S. House of Representatives elections might have been had the state’s districts been drawn to emphasize nonpartisan boundaries. The team re-ran the election 100 times -- using the same votes as in 2012 and tweaking the voting map with only the legal requirements of a redistricting plan in mind. Not once did they get the split of Democratic and Republican seats seen in the actual election.
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They used a statistical algorithm to randomly redraw the boundaries of North Carolina’s 13 congressional districts. The model produced thousands of versions of the redrawn map. All of them were based only on the legal requirements of redistricting, ensuring the districts represented roughly equal numbers of voters and were as geographically compact as possible, without accounting for race or political affiliation.
Next the researchers re-ran the 2012 U.S. House election on a computer and calculated what the outcome would have been for each new version of the map.
”If someone voted for a particular candidate in the 2012 election and one of our redrawn maps assigned where they live to a new congressional district, we assumed that they would still vote for the same political party,” Vaughn said.
After re-running the election 100 times, with a randomly drawn nonpartisan map each time, the average simulated election result was 7 or 8 U.S. House seats for the Democrats and 5 or 6 for Republicans. The maximum number of Republican seats that emerged from any of the simulations was eight. The actual outcome of the election -- four Democratic representatives and nine Republicans – did not occur in any of the simulations.
In North Carolina, Democrats won 51% of the popular vote in congressional races but ended up with only 4 of 13 seats (and they only held that fourth one, Mike McIntyre's NC-07, by 654 votes). However, the study showed Democrats winning on average 7.6 seats.
Now that Mike McIntyre lost re-election, there are 3 Democratic districts and 10 Republican ones. The closest any district gets to being competitive is an R+8 (NC-09 and NC-13). The 8 other Republican-held districts are R+10 or higher. The Democratic districts are D+19, D+21, and D+26.
Let's take a loo at the "creatively" drawn Democratic districts.
A "Before and After" look at NC-04, held by David Price, is particularly striking.
Here is before Republican gerrymandering. As you can see, it is fairly compact.
Here is after Republicans redrew it to keep Raleigh and the Research Triangle in the same district to keep Democrats all in one.
North Carolina's 12th district, recently won by Alma Adams, also stretches the limits of compactness and contiguity. It has Greensboro and Winston-Salem and then goes all the way down to Charlotte.
North Carolina's 1st district, held by G. K. Butterfield, isn't quite as bad as the other two, but it has very oddly drawn branches: